Licorice root is one of the oldest and most frequently employed botanicals
in Chinese medicine. In the United States, licorice products are most often
used as flavoring and sweetening agents in food products. Constituents of
licorice include triterpenoids, such as glycyrrhizin and its aglycone glycy
rrhizic acid, various polyphenols, and polysaccharides. A number of pharmac
eutical effects of licorice are known or suspected (anti-inflammatory, anti
virus, antiulcer, anticarcinogenesis, and others). Licorice and its derivat
ives may protect against carcinogen-induced DNA damage and may be suppressi
ve agents as well. Glycyrrhizic acid is an inhibitor of lipoxygenase and cy
clooxygenase, inhibits protein kinase C, and downregulates the epidermal gr
owth factor receptor. Licorice polyphenols induce apoptosis in cancer cells
. These and other activities of licorice are reviewed, and a rationale is s
uggested for combinations of agents in preventive clinical trials.